JPH11240795A - Epitaxial growth apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an epitaxial growth apparatus equipped with a holding mechanism capable of vertically fixing and holding along the vertical direction without damaging a semiconductor wafer and dropping. SOLUTION: A holding mechanism for holding a semiconductor wafer is attached to a partition wall 2 arranged along a vertical direction in the interior of a reaction chamber and forming a first independent space and a second independent space by partitioning the interior of the reaction chamber. A semiconductor wafer 10 is sucked and fixed to the partition wall 2 through a plurality of through holes 4 formed in a state dispersed in a region bringing into contact with the semiconductor wafer of the partition wall by setting the internal pressure of the first independent space to lower value than the internal pressure of the second independent space by a pressure control means which the holding mechanism has.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epitaxial growth apparatus for epitaxially growing a semiconductor wafer substrate.

[0002]

2. Description of the Related Art At present, the most widely studied and applied silicon epitaxial growth method is H-Si-
This is a Cl-based CVD (Chemical vapor deposition) method.
In this method, a silicon source gas is supplied by a hydrogen carrier onto a silicon substrate heated to a high temperature, and an H-S
A silicon single crystal is deposited and grown through an i-Cl-based reaction. As a silicon source gas, SiCl
₄ , SiHCl ₃ , SiH ₂ Cl ₂ or SiH ₄ are common.

[0003] As a growth furnace apparatus for performing such epitaxial growth, various types have conventionally been used. For example, there is a method in which a substrate is placed on a susceptor in a chamber heated by a radiant heating method using a halogen lamp, an infrared lamp, or the like, and a reaction gas is sent into the chamber.

In the conventional epitaxial growth method and apparatus as described above, a semiconductor wafer is heated in a reference gas atmosphere such as hydrogen while being mounted on a susceptor in a chamber, and then a new material is added to the reference gas. By releasing the gas and supplying it on the wafer surface, a reaction gas in which the material gas is mixed with the reference gas is generated, and the growth is started.

In recent years, as semiconductor wafers have become larger in diameter,
Naturally, an increase in the size of the reactor is inevitable.
For this reason, a single wafer type is generally used as a growth furnace for large diameter wafers. Since this is a single-wafer treatment, the reaction chamber itself can be made compact, and the heating conditions, gas flow distribution, etc. can be easily designed and the uniformity of the epitaxial film characteristics can be increased.

On the other hand, the use of a vertical type which can make the reaction chamber compact, prevent warpage due to its own weight which may cause crystal defects of the wafer, and allow simultaneous epitaxial growth of one or more semiconductor wafers has been studied. ing. In this vertical installation type, for example, a semiconductor wafer can be placed vertically in a cylindrical growth furnace and epitaxial growth can be performed on the surface of the semiconductor wafer by supplying a laminar reaction gas vertically. .

[0007]

However, it has been difficult to vertically arrange and fix the semiconductor wafer vertically in the reaction chamber. When the semiconductor wafer is arranged vertically, for example, a peripheral part of the semiconductor wafer is directly held and fixed by a fixing jig, or a counterbore is provided at a lower portion of the susceptor which is set up with a slight inclination in the reaction chamber. Carve,
A method has been used in which a semiconductor wafer is placed on the susceptor, and the semiconductor wafer is prevented from dropping by its own weight and hanging on the counterbore under the wafer.

In the method of fixing a semiconductor wafer using the fixing jig as described above, not only can the semiconductor wafer be directly touched to cause a defect due to scratches or contamination, but also the peripheral structure including the jig is complicated and the apparatus is difficult to use. There is a problem that this leads to an increase in the overall size.In addition, in the case of utilizing the inclination of the susceptor and the weight of the semiconductor wafer, an extra space is required for the inclination. There was a problem that it could not be rotated.

SUMMARY OF THE INVENTION In view of the above problems, the present invention provides an epitaxial growth apparatus having a holding mechanism capable of holding a semiconductor wafer vertically without damaging the semiconductor wafer and holding the semiconductor wafer without falling even when the semiconductor wafer is rotated. The purpose is to:

[0010]

In order to achieve the above object, an epitaxial growth apparatus according to the first aspect of the present invention provides an epitaxial growth apparatus in which a reaction gas is reduced or thermally decomposed on a surface of a semiconductor wafer at a high temperature inside a reaction chamber. In an epitaxial growth furnace for depositing and growing a Si epitaxial layer, the epitaxial growth furnace is disposed inside a reaction chamber along a vertical direction,
A partition for partitioning the inside of the reaction chamber to form a first independent space and a second independent space; and a holding mechanism for holding the semiconductor wafer on the partition, the holding mechanism comprising:
A plurality of through holes formed in a region of the partition wall where the semiconductor wafer comes into contact with the surface of the second independent space in a state where the semiconductor wafer is exposed to the second independent space; Pressure control means for setting the pressure lower than the internal pressure.

Further, in the epitaxial growth apparatus according to the present invention, in the epitaxial growth apparatus according to the first aspect, the internal pressure difference between the first independent space and the second independent space is 1 × 10 ^4. More than Pa, 5 × 10 ⁴ P
a is within the following range.

Further, in the epitaxial growth apparatus according to the present invention, the opening ratio of the through hole to the surface area of the semiconductor wafer is 1% or more and 5% or more. % Or less.

In the present invention, first and second independent spaces are formed inside the reaction chamber by the partition walls, and the internal pressure of the first independent space is set lower than the internal pressure of the second independent space by the pressure control means. Thereby, the semiconductor wafer contacted with the partition wall so as to expose the surface to the second independent space,
On the back side, it is sucked and held through a through hole formed in the partition.

Therefore, unlike the case where a jig is used, since the member does not directly hold down the semiconductor wafer, if the partition wall is vertically vertical without damaging the wafer,
The semiconductor wafer can be held vertically along the vertical direction.

The pressure difference between the first independent space and the second independent space does not cause the semiconductor wafer to fall due to slight pressure fluctuations and vibrations and also causes a defect in the semiconductor wafer. It is desirable to set an appropriate range so as not to apply stress.

Therefore, as an appropriate range of the pressure difference,
As described in claim 2, 1 × 10 ⁴ Pa or more, 5 ×
It was 10 ⁴ Pa or less. The lower limit is, for example, a diameter of 40
It is a pressure difference that can be sufficiently stably sucked and held even for a so-called large-diameter semiconductor wafer of 0 mm, and the upper limit is an approximate value experimentally obtained as a yield stress in high-temperature heating of silicon at 1000 ° C. or higher. There is a gap of 2 digits or more from 1 × 10 ⁷ Pa, and no defect is generated on the semiconductor wafer.

Further, as many as possible through-holes for suction are uniformly dispersed, so that the pressure is dispersed and the suction holding of the semiconductor wafer becomes more uniform and stable.
Therefore, it is desirable that the opening of the through hole is small.

On the other hand, in the epitaxial growth process, usually, a semiconductor wafer installed in a reaction chamber is heated from the back side through a susceptor so as to reach a reaction condition temperature by radiant heat irradiation from a heating means such as an external heater. I have. Therefore, in order to make the heating by irradiation of the radiant heat uniform, the diameter of the through hole is suitably 0.5 to 1.0 mm. If the diameter is smaller than this, clogging is easy and cleaning is very difficult, and the total number of through-holes is very large. Not practical because of the burden on. Also, when the size exceeds the above range,
The temperature unevenness becomes large, and it becomes difficult to uniformly heat the wafer.

According to the third aspect of the present invention, the through hole having a diameter set within such a range has a total opening ratio to the surface area of the semiconductor wafer of 1% or more and 5% or less. A moderately large number of pores is obtained, and pressure is dispersed to obtain uniform adsorption and retention. For example, if the opening ratio is 5% with respect to a semiconductor wafer having a diameter of 400 mm, the through hole diameter is 1
mm, the number of through holes is about 8000, 0.5m
In the case of m, about 30,000 through holes are obtained.

When the opening ratio is smaller than 1%, the number of through holes is small, and the dispersion of the suction pressure is particularly insufficient for a large-diameter semiconductor wafer having a diameter of 400 mm. On the other hand, if it exceeds 5%, the number of through-holes becomes too large, and if it is desired to have a slope for the through-holes as described later, the interval between adjacent through-holes is too small to be able to make a slope. .

Although it is simple in design to form the through-holes in a direction perpendicular to the partition walls, radiant heat (infrared rays) directly traveling from a heater for heating the semiconductor wafer through the partition walls penetrates. Partially directly hitting the wafer through the hole may cause temperature unevenness. Therefore, by forming the through-hole at an angle from the direction perpendicular to the partition walls, the infrared light entering the through-hole almost hits the hole wall, and the direct irradiation on the wafer is greatly reduced. Is done. As for the angle, for example, the semiconductor wafer contact area of the partition wall is formed of a general susceptor formed using, for example, SiC, quartz, graphite, or the like as a base material, and the susceptor has a thickness of 5 mm and a through-hole diameter of 1.0 mm. From the direction perpendicular to the surface of the partition wall, here the susceptor.
The inclination is preferably not less than 22 degrees and not more than 22 degrees. If it is smaller than this, radiation light from the heating source directly reaches the semiconductor wafer, causing temperature unevenness.

Further, according to the structure of the present invention, a portion including a region where the semiconductor wafer having at least a plurality of through holes is in contact with the partition wall is separated from the surrounding partition wall,
If the semiconductor wafer can be rotated, the semiconductor wafer can be rotated while being held in the vertical direction, and a more uniform heating state can be obtained. For example, a configuration is possible in which a part of the partition wall is configured by a detachable susceptor, and the susceptor is rotatable.

Further, in the configuration of the present invention, the first independent space is separated from the second independent space through which the reactive gas is sent for the epitaxial growth process on the surface of the semiconductor wafer by the partition walls. Because there is this first
A heating means such as a heater can be provided near the partition in the independent space. Further, a heating means can be arranged outside the chamber on the front side of the semiconductor wafer to heat both sides of the wafer. As described above, in the epitaxial growth apparatus of the present invention, since the semiconductor wafer can be heated closer, the heating up to the high temperature conditions required for the reaction can be performed quickly and efficiently. In this case, the installation of the heating means may be designed so as not to affect the pressure control in the first independent space.

In the epitaxial growth apparatus according to the present invention, the number of semiconductor wafers held by the partition holding mechanism is not limited to one. For example, two semiconductor wafers may be arranged in the longitudinal direction of the same partition to perform epitaxial growth simultaneously. A plurality of semiconductor wafers are simultaneously placed in such a manner that two partition walls are provided to face each other, a space sandwiched between both partition walls is a second independent space, a semiconductor wafer is held in each partition wall, and an epitaxial growth process is performed simultaneously. It is good also as a structure which can process.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, as one embodiment of the present invention, a growth apparatus for performing epitaxial growth by vertically arranging one semiconductor wafer in a reaction chamber in a vertical direction will be described with reference to FIG. FIG. (A) is YY
FIG. 3B is a partial side sectional view, and FIG.

In the epitaxial growth apparatus according to the present embodiment, the inside of a vertical reaction chamber 1 having an elliptical cross section and an inverted bell shape is provided.
A partition A separates a room A as a second independent space and a room B as a first independent space separated from each other by a partition wall 2. The partition 2 is partially constituted by the susceptor 3. Specifically, the susceptor 3 can be detachably fixed so as to close the opening at the center of the partition 2. The susceptor 3 may be rotatably fixed to a peripheral partition by a rotation mechanism.

In this embodiment, a description will be given of a case where the susceptor 3 is fixed to the partition 2 using a so-called bayonet method or the like, omitting the rotation mechanism. That is, projections and claws are formed on the inner periphery of the opening of the partition wall 2 and the outer periphery of the susceptor 3, and are locked and fixed to each other by relative rotation. It is assumed that the susceptor 3 is placed with the surface of the semiconductor wafer 10 exposed to the chamber A side. A plurality of through holes 4 are formed in a region where the semiconductor wafer 10 is mounted on the susceptor 3.

In this embodiment, the semiconductor wafer 10
Is 400 mm in diameter, the diameter of the through hole 4 is 1.0 mm, and the total aperture ratio to the wafer surface is about 5%. Therefore, the number of through holes 4 is about 8000. In the arrangement of the through-holes 4, the more uniform the dispersion, the more uniformly the pressure and the heating described later. Various arrangements can be adopted for the arrangement. For example, concentric arrangements as shown in the plan view of FIG. 2, radial arrangements of FIG. 3, or a combination thereof are conceivable. In addition, a random arrangement as shown in FIG. 4 may be used as long as the dispersion is uniform throughout.

Further, in the present epitaxial growth apparatus, a reaction gas containing a silicon material gas is supplied only into the chamber A outside the reaction chamber 1 and only a reference gas (hydrogen gas) containing no material gas is supplied into the chamber B. A supply unit (not shown) and a pressure control unit (not shown) for controlling the A room pressure and the B room pressure respectively are provided.

A heater 5 driven and controlled from outside the reaction chamber 1 is disposed near the susceptor 3 in the chamber B. The semiconductor wafer 10 is quickly and efficiently heated from the rear surface side via the susceptor 3 by the heater 5 located in the vicinity as described above.

In the step of epitaxial growth on the surface of the semiconductor wafer 10 in the epitaxial growth apparatus having the above-described structure, first, a robot arm or the like is used to suction-fix the tip of the susceptor 3 through a part of the through hole 4 of the susceptor 3. The semiconductor wafer 10 is put into the reaction chamber 1 from the chamber B side, and the susceptor 3 is fixed to the partition 2 so that the wafer surface is exposed to the chamber A side.

Thereafter, the internal pressure of the chamber A is set to 9 × 10 ⁴ Pa and the internal pressure of the chamber B is set to 5 × 10 ⁴
Pa, and the pressure difference between the two chambers was 4 × 10 ⁴ Pa. By setting the internal pressure of the chamber A higher than that of the chamber B in this manner, even if the suction and fixation by the robot arm is released, the semiconductor wafer 10 will not generate a final defect in the semiconductor wafer via the through hole 4 of the susceptor 3. Is strongly fixed by suction.

While maintaining the internal pressures of the chambers A and B at the above-mentioned values, heating by the heater 5 in the chamber B is started. High temperature required for the epitaxial growth reaction of the semiconductor wafer 10;
For example, when the temperature reaches 1000 ° C., the reaction gas is sent from above to below (or from below to above) into the A chamber,
Initiate an epitaxial growth reaction. Due to the pressure difference between the chambers A and B maintained during this process, the semiconductor wafer 10 is always stably held vertically and stably without causing any scratches or warpage which may cause defects. A high quality semiconductor wafer having a film formed thereon is obtained.

In the above embodiment, only one semiconductor wafer 10 is processed at a time.
The same reaction chamber may be partitioned by two partitions facing each other, or the middle chamber of a double chamber may be used as a partition,
By adopting a design for the partition wall, a configuration may be employed in which one or more semiconductor wafers can be processed simultaneously.

Further, by providing a rotation mechanism for rotating the susceptor 3, the semiconductor wafer 10 can be rotated during the epitaxial growth process, and the heating state and the formation of the epitaxial growth film can be made more uniform.

[0036]

As described above, according to the epitaxial growth apparatus of the present invention, the semiconductor wafer can be stably held vertically in the vertical direction in the reaction chamber while having a simple structure, which causes defects. The generation of such scratches and warpage can be avoided, and there is an effect that a better epitaxially grown film can be formed than before.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an epitaxial growth apparatus according to an embodiment of the present invention, in which (a) is a side sectional view of a YY part, and (b) is a transverse sectional view of a XX part.

FIG. 2 is a schematic plan view showing an example of an arrangement of through holes.

FIG. 3 is a schematic plan view showing another example of an arrangement of through holes.

FIG. 4 is a schematic plan view showing another example of an arrangement of through holes.

[Explanation of symbols]

 1: Reaction chamber 2: Partition wall 3, 13, 23: Susceptor 4, 14, 24: Through hole 5: Heater 10: Semiconductor wafer

Continuation of the front page (72) Inventor Shinji Nakahara 555 Nakanoya, Annaka-shi, Gunma Pref.

Claims (3)

[Claims] 1. The method according to claim 1, wherein the reaction gas is reduced or thermally decomposed on the surface of the semiconductor wafer at a high temperature inside the reaction chamber.
An epitaxial growth apparatus for depositing and growing an epitaxial layer, comprising: a partition wall arranged in a vertical direction inside a reaction chamber to partition the inside of the reaction chamber to form a first independent space and a second independent space; A holding mechanism for holding the semiconductor wafer,
A plurality of through-holes formed in a region of the partition wall where the semiconductor wafer comes into contact with the surface of the semiconductor wafer in a state where the semiconductor wafer is exposed to the second independent space; Pressure control means for setting the internal pressure lower than the internal pressure of the second independent space. 2. The method according to claim 1, wherein an internal pressure difference between the first independent space and the second independent space is in a range of 1 × 10 ⁴ Pa or more and 5 × 10 ⁴ Pa or less. The epitaxial growth apparatus according to the above. 3. The epitaxial growth apparatus according to claim 1, wherein an opening ratio of the through hole to a surface area of the semiconductor wafer is in a range of 1% or more and 5% or less.